Circuit breaker



Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Pennsylvania Application March 27, 1947, Serial No. 737,592

10 Claims.

This invention relates to circuit breakers and more particularly to circuit breakers of the snapacting type.

An object of the invention is to provide an improved snap-acting circuit breaker that is simple, reliable in operation and inexpensive to manufacture.

Another object of the invention is to provide an improved snap-acting circuit breaker which is manually operable to both open and closed positions and which is trip-free of the manual operator.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed description of one embodiment thereof when read in connection with the accompanying drawings, in which:

Figure l is a side elevational View partly in section and having the cover plate partly broken away of a two pole circuit breaker embodying the principles of the invention, the mechanism being shown in the closed position,

Fig. 2 is a view similar to Fig. 1 but showing the mechanism in the manually opened position;

Fig. 3 is a view similar to Fig. l but showing the mechanism in the tripped open position,

Fig. 4 is a view similar to Fig. 1 but showing the mechanism trip open with the manual operating handle held in the closed position, and

Fig. 5 is a plan view of the resilient snap-acting switch member.

Referring to Fig. 1 of the drawings, the circuit breaker comprises generally a casing l of molded insulating material, a cover plate l3 also of insulating material, operating mechanism indicated generally at i5 and a trip device indicated generally at H.

The operating mechanism comprises a pair of snap-acting resilient switch members l9 and 2| having movable contact members 23 and 25 secured respectively to the ends thereof. The movable contacts 23 on the switch member l9 are adapted to cooperate with stationary contacts 21 on the inner ends of conductor 29 and 3| which extend in opposite directions to the exterior of the casing II when they form terminal connecl tors. The movable contacts 25 on the switch member 2| cooperate with fixed contacts 33 and 35 on conductors 31 and 39. The conductor 31 extends at right angles through an opening in one end wall of the casing II and forms a terminal 4|. The conductor 39 is secured to the other end wall of the casing and its lower end is connected by means of a flexible shunt conductor 43 to one end of a bimetal element 45 which has its other end rigidly secured to a conductor 47. The conductor 41 extends at right angles through the end wall of the casing and forms a terminal 9. The terminals 29, 3|, 4| and 49 serve to connect the circuit breaker in the electrical circuit which it is to control.

The switch members is and 2| are alike for which reason only one will be described. The snap-acting switch members (Fig. 5) each comprise a fiat strip of spring material slotted at 5| and 53 to provide a pair of parallel outer tension arms 55 and 5'! and a central pair of compression arms 59 and {5| in spaced relation. The compression arms 5!! and Bi are formed by dividing a single central arm transversely near its center so that the inner ends of the arms 58 and iii are in spaced relation.

Disposed between the ends of the compression arms 59 and El of each of the switch members is an arcuate spring member 63, the spaced ends of which are formed to receive the ends of the arms 59 and SI. The spring members 63 are secured to a vertically disposed operating rod 55 of insulating material for movement therewith and serve to support the switch members thereon. The spring members 63 have an initial tension tending to separate their ends thereby applying endwise forces to the arms 59 and El which tends to force the arms apart.

The upper end of the operating rod 65 is provided with a head Bl for cooperating with a cupshaped member 69 of insulating material which threadedly engages a push button ll. Disposed within the cup-shaped member 69 is a coil spring 73 which is compressed between a washer l5 and the head ll of a rod 19. The rod 79 extends upwardly through an opening in the washer l5 and is provided with a small head 8! which engages the washer to limit the expansion of the spring '13. The small head 8| of the rod 19 is adapted to slide in an opening 83 in the push button for a purpose hereinafter to be described.

Referring to Fig. l of the drawings, the circuit breaker is shown in the closed position with the operating rod biased inwardly and the movable contacts 23 and 25 cooperating respectively with their associated stationary contacts 21, 33 and 35 to close the circuits through the breaker. The circuit breaker is opened by moving the operating rod 65 outwardly which movement forces the compression arms 59 and SI of the resilient switch members I9 and 2| over center above the planes of the tension arms 55 and 51. This overcenter movement is effected partl by the resilience of the spring members 63 and partly by the resilience of the compression arms 596l. As soon as the compression arms 59-6! have moved over center relative to the plane of the resilient switch members Iii-2|, the outer ends of the switch members which carry the movable contacts will move downwardly to the open position with a snap action under the influence of the compression arms Bil-6i and the arcuate spring members 63 which tend to spread the compression arms apart. The opening movement of the contact carrying ends of the switch members is and 2| is limited, respectively, by means of stops 85 and 81 formed integral with the casing II.

The operating rod 65 is moved outwardly to manually open the contacts by manually pulling out the push button H. This acts through the cup-shaped member 69 and the head 61 of the operating rod 55 to draw the rod outwardly and effect opening of the contacts. The circuit breaker is shown in the manually opened position in Fig. 2.

From the open position (Fig. 2) the circuit breaker may be closed by movement of the operating rod 65 inwardly to the Fig. 1 position which is accomplished by pushing the push button H inwardly. The push button moves inwardly until the head 'I'! of the rod 78 engages the head 61 of the operating rod 65. Thereafter the push button acts through the spring'l3 which is of suflicient strength to overcome the resilience of the spring members 63 and the compression arms Bil-6| and move the compression arms over center below the plane of the switch members l9 and 2|. As soon as the compression arms have passed below the plane of the switch members, the outer ends of the switch members move upwardly to close the contacts with a snap action.

The circuit breaker is automatically tripped open in response to overload currents by operation of the trip device IT. The trip device comprises the bimetal element 45 which is connected in the circuit to be traversed by the current flowing in one of the poles of the breaker. A latch member 89 on the free end of the bimetal element 45 normally engages a head 9| of a spring biased plunger 93 to releasably restrain the plunger against operation by the spring. The plunger 93 is slidable in a guide member 95 rigidly supported on cross member 97 mounted on a boss 99 integral with the casing l l and a corresponding bossv (not shown) on the cover plate I3. The plunger 93 is biased upwardly by means of a coil spring I01 compressed between the cross member 97 and the head 9| of the plunger, but, with normal rated current in the circuit, is normally restrained by the latch 89 on the bimetal element 45.

Upon the occurrence of an overload current in the circuit which includes the bimetal element 45, the bimetal element becomes heated and when heated a predetermined amount deflects toward the right (Figs. 1 and 2) to unlatch the plunger 93, whereupon the spring IBI expands and drives the plunger 93 outward. At this movement, the plunger 93 moves the operating rod 65 outwardly to effect opening of the contacts in the previously described manner.

In order to reset and relatch the trip device and the actuating plunger the push button 1| is pulled out to its extreme outward position. Figure 3 shows the circuit breaker in the tripped open position in which, it will be seen, that the push button is moved outwardly to an interme-' diate or indicating position and that the spring 73 is partially compressed. A lever EH33 pivoted on a pin m5 supported in an opening in the side wall of the casing H and in a companion opening (not shown) in the cover plate [3 is bifurcated at one end and straddles the lower end of the plunger 93. The left-hand end of the lever W3 is pivotally connected to a link I 01. The upper end of the link I0! is bifurcated to straddie the switch members I9 and Z! and the cupshaped member 69 associated with the push but ton. Each of the forks of the bifurcated open end of the link i9? is provided with a pin Hi9 (only one being shown) which project into suitable openings in opposite sides of the member 69. To reset the mechanism after it has been tripped open, the push button H is pulled outwardly as far as it will go. This acts through the link [Ell to rock the lever Hi3 clockwise during which movement the forks of the lever I03 engage a head H i on the lower end of the plunger 93 thereby moving the plunger downwardly to compress the spring [GI and reengage the head 9! of the plunger under the latch member 89.

After the mechanism has been reset and relatched, the contacts are closed by pressing the button ll inwardly to its extreme position in the previously described manner.

. Provision is made for efiecting trip-free operation of the circuit breaker, that, is, the circuit breaker may be tripped and moved to the open position even though the push button is held in the on or extreme inward position. In Figure 4 the circuit breaker is shown in the tripped open position with the push button held in before the resetting operation. It will be noted that in the trip-free position of the-parts the spring 13 is substantially compressed, since the spring [BI is stronger than the spring 13, and that the head 3! of the rod 79 has moved to the upper end of the opening 83 provided for that purpose in the push button.

Following a trip-free operation the breaker is reset and the contacts reclosed in the previously described manner.

From the foregoing description, it will be seen that there is provided an improved circuit breaker having a first spring associated with the contacts to provide snap action opening and closing of the contacts, a second spring stronger than the first spring for transmitting closing movement of the handle to the operator to close the contacts and for permitting opening movement of the operator irrespective of the position of the handle and an actuating spring stronger than the first and second springs combined operable when released to effect automatic opening of the contacts irrespective of the position of the handle.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising a plurality of sets of separable contact means, a plurality of snap acting switch members, a support member common to said switch members, resilient means mounting said switch members on said support member to permit movement of said switch members from one position to another relative to said support member, manual means-for moving said support member to. cause movement of said releasable member.

2. A circuit breaker comprising a plurality of sets of separable contact means, a plurality of snap acting switch members, an operating rod supporting said switch members and movable longitudinally to efiect opening and closing of said contact means, spring means mounting said switch members on said operating rod to permit movement of the free ends of said switch mem- I bers relative to said operating rod upon movement of said rod, manual means for moving said operating rod to open and close said contact means, means comprising an actuating plunger biased to move said operating rod to automatically open said contact means, means permitting automatic opening movement of said operating rod irrespective of the position of said manual means, a latch normally restraining said plunger, and a bimetal element operable in response to overload currents to actuate said latch and re lease said plunger.

3. A circuit breaker comprising separable contact means, a switch member comprising a strip of resilient material slotted to form a plurality of parallel arms connected together at the ends of said trip, one of said arms being divided transversely at a point near its center to form a pair of opposing compression members, an operating rod for supporting and actuating said switch member, spring means on said operating rod for engaging the opposing ends of said compression members to support said switch member on said operating rod and to permit movement of the switch member relative to said operating rod upon movement of said rod, manual means associated with one end of said operating rod for moving said rod to eiiect manual opening and closing of said contact means, a releasable actuating rod associated with the other end or" said operating rod biased to move said operating rod to eiiect automatic opening of said contact means, latch means normally restraining said releasable actuating rod, and electroresponsive means operable in response to overload currents to actuate said latch to release said releasable actuating rod.

4. A circuit breaker comprising separate contact means, a switch member comprising a strip of resilient material slotted to form a plurality of parallel arms connected together at the ends of said strip, one of said arms being divided transversely at a point near its center to form a pair of opposing compression members, an operating rod for supporting and actuating said switch member, spring means on said operating rod for engaging the opposing ends of said compression members to support said switch member on said operating rod and to permit movement of the switch member relative to said operating rod upon movement of said rod, manual means associated with one end of said operating rod for moving said rod to efiect manual opening and closing of said contact means, releasable means associated with the other end of said operating rod operable when released to move said operating rod to effect automatic opening of said contact means, latch means normally restraining said releasable means, electroresponsive means operable in response to overload currents to actuate said latch and release said releasable means, and a lost motion connection between said manual means and said operating rod permitting opening movement of said operating rod irrespective of the position of said manual means.

5. A circuit breaker comprising separate contact means, a switch member comprising a strip of resilient material slotted to form a plurality of parallel arms connected together at the ends of said strip, one of said arms being divided transversely at a point near its center to form a pair of opposing compression members, an operating rod for supporting and actuating said switch member, spring means on said operating rod for engaging the opposing ends of said compression members to support said switch member on said operating rod and to permit movement of the switch member relative to said operating rod upon movement of said rod, manual means associated with one end of said operating rod for moving said rod to effect manual opening and closing of said contact means, releasable means associated with the other end of said operating rod operable when released to move said operating rod to effect automatic opening of said contact means, electroresponsive means normally restraining said releasable means, said electroresponsive means being operable in response to overload currents to release said releasable means, means intermediate said manual means and said operating rod permitting opening movement of said operating rod irrespective of the position of said manual means, and resetting means operated by said manual means to reset said releasable means.

6. A circuit breaker comprising separable contact means, a switch member comprising a strip of resilient material slotted to form a plurality of parallel arms connected together at the ends of said strip, one of said arms being divided transversely at a point near its center to form a pair of opposing compression members, an operating rod for supporting and actuating said switch member, spring means on said operating rod for engaging the opposing ends of said compression members to support said switch member on said operating rod and to permit movement of the switch member relative to said operating rod upon movement of said rod, manual means associated with one end of said operating rod for moving said rod to effect manual opening and closing of said contact means, a releasable actuating rod associated with the other end of said operating rod operable when released to move said operating rod to efiect automatic opening of said contact means, spring means between said manual means and said operating rod to permit automatic opening movement of said operating rod irrespective of the position of said manual means, latch means normally restraining said releasable actuating rod, electroresponsive means operable in response to overload currents to actuate said latch means and release said releasable actuating rod, and a linkage operable by said manual means to reset and relatch said releasable actuating rod.

'7. A circuit breaker comprising stationary and movable contact means, a snap-acting switch member supporting said movable contact means, an operating member connected to operate said switch member in a manner to effect opening and closing of said contact means with a snap action, manual means for manually moving said operating member to open and close said contact means, a first spring between said operating member and said. manual means to permit opening movement of said operating member irrespective of the position of said manual means, a releasable actuator operable when released to move said operating member to eifect opening of said contact means, a second spring biasing said actuator to move said operating member in opening direction, said second spring means being of greater strength than said first spring means to thereby effect opening movement or" said operating member irrespective of the position of said manual means, and trip means operable in response to overload currents to effect release of said actuator.

8. A circuit breaker comprising stationary and movable contact means, snap-acting switch means supporting said movable contact means, an operating member connected to operate said switch means to effect opening and closing of said contact means, first spring means associated with said switch means for causing said switch means to move said contact means to open and closed positions with a snap action, manual means for manually moving said operating member to open and closed positions, second spring means between said operating member and said manual means for permitting automatic opening movement of said operating member irrespective of the position of said manual means, said second spring means being of greater strength than said first spring means to transmit closing movement of said manual means to said operating member, a releasable actuator operable when released to move said operating member to effect automatic opening of said contact means, a third spring means biasing said actuator to move said operating member in opening direction, said third spring means being of greater strength than said second spring means to thereby effect automatic opening movement of said operatingmember irrespective of the position of said manual means, and trip means operable in response to overload currents to release said actuator.

9. A circuit breaker comprising a plurality of sets of separable contact means, a plurality of snap-acting switch members, a support member common to all of said switch members, resilient means mounting said switch members on said support member to permit movement of said switch members from one position to another relative to said support member, manual means for moving said support member to cause movement of said switch members relative to said support member to effect manual opening and closing of said contact means, a reciprocably movable member biased to move said support member to effect automatic opening of said contact means, latch means normally restraining said re- ,ciprocably movable member, trip means responsive to overload currents for actuating said latch means to effect release of said reciprocably movable member, and resilient means between said support member and said manual means permitting opening movement of said support member in any position of said manual means.

10. A circuit breaker comprising a, plurality of sets of separable contact means, a plurality of snap-acting switch members, an operating rod supporting all of said switch members and movable longitudinally to effect opening and closing of saidcontact means, spring means mounting said switch members on said operating rod to permit movement of the free ends of said switch members relative to said operating rod upon movement of said rod, manual means movable between open and closed positions for moving said operating rod to effect manual opening and closing of said contact means, means comprising an actuating plunger disposed in axial alignment with said operating rod and biased to move said operating rod to effect automatic opening of said contact means, a latch releasably restraining said plunger, a bimetal element operable in response to overload currents to actuate said latch and release said plunger, and spring means permitting automatic opening movement of said operating rod even though said manual means is held in the closed position.

CLARE A. STUMP, JR. RALPH D. JESSEE.

REFERENCES CITED The following references are of record in the 

